Fpc Build

fpc-build

Build-time configuration for Free Pascal Compiler and Lazarus projects that consume mORMot 2: command-line fpc invocations, mode selection (-Mobjfpc, -Mdelphi), unit and include search paths into $MORMOT2_PATH/src/{core,orm,rest,soa,db,crypt,net,app,lib}, .lpi project files driven by lazbuild, and cross-target builds (-T, -P) for ARM, AArch64, and Linux from a Windows host. This skill teaches WHY/WHICH flags to set; the wrapper script scripts/fpc-build.sh covers WHEN/HOW to drive them from CI. It assumes the runtime/topology decisions of mormot2-deploy (services, reverse proxy, static libs) and stops where Delphi begins: dcc32, dcc64, .dproj, and MSBuild all belong in delphi-build.

When to use

• Adding -Fu (unit) and -Fi (include) search paths to an fpc command line so a project picks up mormot.core.base.pas, mormot.orm.core.pas, and the rest of the namespace tree under $MORMOT2_PATH/src.
• Choosing between -Mobjfpc (mORMot's required default) and -Mdelphi (compatibility mode) for a given source tree, and pairing it with -Sci so C-style operators like += and ^= parse.
• Configuring a Lazarus .lpi project file: search paths, custom build modes (Debug, Release), package dependencies, and triggering builds from CI via lazbuild file.lpi --build-mode=Release.
• Cross-compiling from a Windows host to ARM Linux (-Tlinux -Parm), AArch64 Linux (-Tlinux -Paarch64), or 32-bit Linux (-Tlinux -Pi386) using a pre-built FPC cross toolchain.
• Wiring scripts/fpc-build.sh into CI: pinning MORMOT2_PATH, parsing the BUILD_RESULT exit=... errors=... warnings=... trailer, and switching between fpc (for .dpr/.lpr) and lazbuild (for .lpi) automatically based on file extension.
• Toggling FPC-specific defines: FPC_X64MM (use mORMot's x86_64 memory manager), FPCMM_BOOST (boost mode), FPC_HAS_FEATURE_STACKCHECK family.
• Diagnosing Fatal: Can't find unit mormot.core.base used by ..., which on FPC always traces back to a missing -Fu, the wrong mode (-Mtp), or a stale lib/ output dir from a prior architecture.

When NOT to use

• Delphi command-line builds: dcc32, dcc64, .dproj, MSBuild, ` properties, rsvars.bat. Use **delphi-build**. (Conditional defines such as STATICSQLITE apply to both compilers; delphi-build` covers them on the Delphi side, this skill on the FPC side.)
• Runtime deployment: bundling static C archives with the binary, registering a Windows Service, writing a systemd unit, choosing a reverse proxy. Use mormot2-deploy.
• In-process TLS, ACME, HTTP engine selection. Use mormot2-net.
• REST routes, SOA contracts, TRestServer lifecycle. Use mormot2-rest-soa.
• RawUtf8, TSynLog, TDocVariant, RTTI conventions used in the examples. Use mormot2-core.

Core idioms

1. Compile a .dpr or .lpr directly with fpc

When you do not have an .lpi (a small tool, a CLI, a test harness), fpc takes search paths on the command line. -Fu adds a unit search path, -Fi an include search path, -FE sets the executable output dir, -FU sets the unit (.ppu) output dir, and -B forces a rebuild of every unit.

SRC="$MORMOT2_PATH/src"
fpc \
  -Mobjfpc -Sci \
  -Fu"$SRC" -Fu"$SRC/core" -Fu"$SRC/orm" -Fu"$SRC/rest" \
  -Fi"$SRC" -Fi"$SRC/core" \
  -FE./bin -FU./lib \
  -dDEBUG -B \
  myserver.lpr

-Mobjfpc enables the Object Pascal mode mORMot 2 is written against; -Sci adds C-style operators (+=, -=, *=, /=) that mORMot uses heavily. Drop -Sci and the compiler will reject perfectly valid mORMot source with cryptic syntax errors. scripts/fpc-build.sh wraps exactly this pattern: it expands the path list under $MORMOT2_PATH/src, drops any subfolder that does not exist, and quotes each -Fu/-Fi argument so spaces in the install path do not split the token. See references/fpc-modes-and-flags.md for the full flag table.

2. Build an .lpi through lazbuild

Lazarus stores project state in an .lpi file: search paths, build modes (Default, Debug, Release, plus any custom modes), package dependencies, target OS/CPU. lazbuild is the headless builder that consumes the same .lpi the IDE writes, with no GUI.

# Build the default mode.
lazbuild myserver.lpi

# Build a specific mode.
lazbuild myserver.lpi --build-mode=Release

# Build all modes in a row (CI matrix).
lazbuild myserver.lpi --build-all

# Override the OS/CPU at the command line (cross-compile target).
lazbuild myserver.lpi --build-mode=Release --os=linux --cpu=aarch64

# Skip dependency checks (useful when a sibling package has its own build).
lazbuild myserver.lpi --skip-dependencies

Custom search paths configured in the IDE under Project Options | Compiler Options | Paths are written into the .lpi and travel with source control. Avoid paths added under Tools | Options | Files: those live in IDE config and CI runners do not have them. See references/lazbuild-and-lpi.md for the .lpi schema and per-mode override rules.

3. Cross-compile from Windows to Linux/ARM

FPC ships separate compiler binaries per host/target pair, plus a cross-binutils toolchain. The host invokes fpc (the Windows binary), passes -T -P to switch the target, and fpc calls into the cross-assembler (-as) and cross-linker (-ld) found on PATH or in $FPCDIR/bin.

# Windows host -> AArch64 Linux target.
fpc -Mobjfpc -Sci \
  -Tlinux -Paarch64 \
  -Fu"$MORMOT2_PATH/src" -Fu"$MORMOT2_PATH/src/core" \
  -FE./bin/aarch64-linux \
  -FU./lib/aarch64-linux \
  myserver.lpr

The output unit dir (-FU) MUST be partitioned per target: a .ppu built for linux/aarch64 is binary-incompatible with win64/x86_64 and the linker will silently pick the wrong one if both share lib/. lazbuild partitions automatically when Project Options | Paths | Unit output directory contains $(TargetOS)-$(TargetCPU). Hand-rolled fpc calls must do the same. See references/cross-compilation.md for host triplets, runtime DLL/SO requirements, and the -XR flag for offline cross-builds.

4. Toggle FPC-specific defines consistently

mORMot 2 has FPC-only conditional symbols that toggle the bundled memory manager and other runtime features. Set them in exactly one place per build:

• FPC_X64MM — replace FPC's default heap with mORMot's mormot.core.fpcx64mm (faster on multi-threaded server workloads). Set via -dFPC_X64MM on the command line or under Custom Options in the .lpi.
• FPCMM_BOOST — enables aggressive small-block allocation in fpcx64mm (further speedup, slightly more memory).
• FPCMM_DEBUG — adds leak/double-free detection at the cost of throughput. Pair with a development build, never production.
• FPCMM_NOASSEMBLER — falls back to pure-Pascal allocator (slower but portable to any CPU).

Do not mix: a project that sets FPC_X64MM in the .lpi Release mode AND inherits -dFPC_X64MM from lazbuild --build-mode=Release ends up with the define set twice, which is harmless until a dependency .inc does {$IFDEF FPC_X64MM}{$DEFINE FPCMM_BOOST}{$ENDIF} and now you get boost mode without asking. Search the tree (rg -F '{$DEFINE FPC_X64MM}', rg -F '{$UNDEF FPC_X64MM}') before adding a new global.

5. Run via scripts/fpc-build.sh

The wrapper resolves MORMOT2_PATH, picks fpc versus lazbuild from the project file extension, injects search paths under $MORMOT2_PATH/src, captures stdout, parses errors and warnings, and emits a single trailer line CI can grep:

export MORMOT2_PATH=/src/mormot2
scripts/fpc-build.sh --project myserver.lpr
# ...build output...
# BUILD_RESULT exit=0 errors=0 warnings=2 first=

scripts/fpc-build.sh --lpi myserver.lpi
# ...build output...
# BUILD_RESULT exit=0 errors=0 warnings=0 first=

Exit codes map cleanly: 0 success, 2 MORMOT2_PATH unset/invalid, 5 project missing, 6 fpc/lazbuild not on PATH, 7 build failed (errors > 0). CI scripts should grep for the BUILD_RESULT trailer rather than rely on $? alone, because some FPC error patterns can leave $? at 0 even when the build produced unresolved-unit fatals.

Common pitfalls

• Missing -Sci. mORMot 2 source uses +=, -=, *=, and /= everywhere. Without -Sci, the compiler emits Error: Illegal expression or Error: ":=" expected at the first such line, with no hint that a single missing flag is the cause. Always pass -Sci (or set Compiler Options | Parsing | C-style operators in the .lpi). scripts/fpc-build.sh passes it unconditionally on the fpc path; .lpi projects must enable it explicitly per build mode.
• Wrong mode for mORMot 2 (-Mtp or -Mdelphi). mORMot 2 requires -Mobjfpc. -Mdelphi compiles a subset but breaks on operator overloading and inline classes; -Mtp (Turbo Pascal) does not get out of unit 1. Symptom: Error: Operator is not overloaded or Error: Identifier not found 'inline'. Set -Mobjfpc on the command line or under Compiler Options | Parsing | Syntax mode in the .lpi.
• Lazarus IDE-only paths in .lpi not propagating to lazbuild. Paths added via Tools | Options | Files | Other unit files live in the IDE config (environmentoptions.xml), not in the .lpi. The IDE finds them; lazbuild does not. Symptom: builds work in the IDE, fail in CI with Fatal: Can't find unit .... Move every dependency path into the .lpi under Project Options | Compiler Options | Paths | Other unit files, or pass --add-package / --ws=... flags to lazbuild.
• Shared lib/ directory across targets. fpc -FU./lib writes .ppu files into one directory regardless of target OS/CPU. Switch from win64 to linux/aarch64 without rm -rf lib/ (or without partitioning into lib/$(TargetOS)-$(TargetCPU)) and the linker pulls a Win64 .ppu into a Linux build, with no error until link time when symbol mangling differs. Always partition: -FU./lib/$fpctarget. scripts/fpc-build.sh does not auto-partition; CI scripts must clean lib/ between targets.
• MORMOT2_PATH set per shell, missing from CI. Local devs put export MORMOT2_PATH=/src/mormot2 in .bashrc; CI runners have nothing. scripts/fpc-build.sh exits 2 ("MORMOT2_PATH unset") with a clear message, but a hand-rolled fpc call just produces Fatal: Can't find unit mormot.core.base with no hint. Set MORMOT2_PATH in the CI job's environment block, and assert it is non-empty as the first step of the build.
• fpc.cfg shadowing command-line flags. FPC reads fpc.cfg from $FPCDIR/etc/, ~/.fpc.cfg, and the working directory in that order. A user-level ~/.fpc.cfg with -Fu/usr/local/lib/fpc/3.2.2/units/$FPCTARGET is fine for non-mORMot work but can pull in mismatched .ppu versions of shared units (fpwidestring, cwstring). Pass -n to ignore the default config and rely entirely on the explicit flags scripts/fpc-build.sh passes, when the build host is shared or untrusted.
• Mixed FPC versions across CI runners. mORMot 2 requires FPC 3.2.0 or newer; some skip-list features need 3.2.2. A runner with FPC 3.0.4 produces Fatal: Can't find unit Generics.Collections because that unit only landed in 3.2.0. Pin the FPC version per runner (fpc -iV should print 3.2.2 or newer), and document the minimum in the project README. Lazarus pinning is separate: a Lazarus 2.0 IDE can drive an FPC 3.2.2 backend, but the .lpi schema migrated at Lazarus 2.2 and old IDEs strip new properties on save.
• Spaces in MORMOT2_PATH not quoted. fpc -Fu/c/Program Files/mormot2/src parses as -Fu/c/Program plus a positional argument Files/mormot2/src, which fails with Fatal: Compilation aborted. Always quote: -Fu"$MORMOT2_PATH/src". scripts/fpc-build.sh quotes correctly; ad-hoc eval calls usually do not. (Even better: install mORMot under a path with no spaces; Windows + MSYS2 path mangling makes spaces fragile no matter how careful the quoting.)

See also

• $MORMOT2_DOC_PATH/mORMot2-SAD-Chapter-26.md - Installation and Compilation
• references/fpc-modes-and-flags.md
• references/lazbuild-and-lpi.md
• references/cross-compilation.md
• scripts/fpc-build.sh - the build wrapper this skill teaches
• delphi-build for Delphi dcc32/dcc64/.dproj/MSBuild builds
• mormot2-deploy for runtime topology, services, static-library bundling
• mormot2-core for RawUtf8, TSynLog, and the unit conventions every snippet above leans on

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: flydev-fr
• Source: flydev-fr/mormot2-superpowers
• License: MIT

Install and usage instructions live in the source repository linked above.